Effect of Temperature, pH, and Metal Ion Binding on the Secondary Structure of Bacteriorhodopsin:  FT-IR Study of the Melting and Premelting Transition Temperatures†

Biochemistry ◽  
2001 ◽  
Vol 40 (39) ◽  
pp. 11819-11827 ◽  
Author(s):  
Colin D. Heyes ◽  
Mostafa A. El-Sayed
Keyword(s):  
Secondary Structure ◽  
Metal Ion ◽  
Effect Of Temperature ◽  
Ion Binding ◽  
Transition Temperatures ◽  
Metal Ion Binding ◽  
Ft Ir ◽  
Ir Study

Interaction of human serum albumin with oxovanadium ions studied by FT-IR spectroscopy and gel and capillary electrophoresis

2001 ◽  
Vol 79 (10) ◽  
pp. 1415-1421 ◽  
Author(s):  
M Purcell ◽  
J F Neault ◽  
H Malonga ◽  
H Arakawa ◽  
H A Tajmir-Riahi
Keyword(s):  
Capillary Electrophoresis ◽  
Human Serum Albumin ◽  
Ir Spectroscopy ◽  
Metal Ion ◽  
Binding Mode ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Ft Ir ◽  
Ft Ir Spectroscopy ◽  
Oxovanadium Compounds

Some oxovanadium compounds have shown potential to inhibit RNase activity, while at the same time not inhibiting DNase activity. Some vanadyl complexes also inhibit protein synthesis in rabbit reticulocytes, but induce activation of protein–tyrosine kinase. To gain an insight into the interaction of oxovanadium ions with proteins, the present study was designed to examine the bindings of VOSO4 and NaVO3 salts with human serum albumin (HSA) in aqueous solution at physiological pH with metal ion concentrations of 0.0001 to 1 mM and HSA (fatty acid free) concentration of 2% w/v. Gel and capillary electrophoresis (CE) and Fourier transform infrared (FT-IR) spectroscopic methods were used to determine the metal ion binding mode, association constant, and the secondary structure of the protein in the presence of the oxovanadium compounds. Gel electrophoresis results showed that a maximum of 20 vanadyl cations (VO2+) are bound per HSA molecule with strong (K1 = 7.0 × 107 M–1) and weak (K2 = 6.5 × 105 M–1) bindings. Similarly, capillary electrophoresis showed two major bindings for vanadyl cation with K1 = 1.2 × 108 M–1 and K2 = 8.5 × 105 M–1, whereas vanadate (VO–3) has only a weak binding affinity (K = 6.0 × 103 M–1) with HSA molecule. The VO–3 binds mainly to the lysine ε-amino NH+3 groups, while VO2+ binds possibly to the histidine nitrogen atom and the N-terminal of the α-amine residue. Infrared spectroscopic analysis showed metal ion binding results in major protein secondary structural changes from that of the α-helix (55.0 to 43–44%) to the β-sheet (22.0 to 23–26%), β-antiparallel (12.0 to 13–16%), and turn (11.0 to 17–18%), at high metal ion concentration. The observed spectral changes indicate a partial unfolding of the protein structure, in the presence of oxovanadium ions.Key words: oxovanadium, protein, binding mode, binding constant, secondary structure, electrophoresis, FT-IR spectroscopy.

Interaction of RNase A with VO3-and VO2+Ions. Metal Ion Binding Mode and Protein Secondary Structure

1999 ◽  
Vol 17 (3) ◽  
pp. 473-480 ◽  
Author(s):  
M. Purcell ◽  
A. Novetta-Delen ◽  
H. Arakawa ◽  
H. Malonga ◽  
H. A. Tajmir-Riahi
Keyword(s):  
Secondary Structure ◽  
Metal Ion ◽  
Protein Secondary Structure ◽  
Binding Mode ◽  
Rnase A ◽  
Ion Binding ◽  
Metal Ion Binding

Photophysical Characterisation, Metal Ion Binding and Enantiomeric Recognition of Chiral Ligands Containing Phenazine Fluorophore

2004 ◽  
Vol 69 (4) ◽  
pp. 885-896 ◽  
Author(s):  
Luisa Stella Dolci ◽  
Péter Huszthy ◽  
Erika Samu ◽  
Marco Montalti ◽  
Luca Prodi ◽  
...  
Keyword(s):  
Metal Ion ◽  
Photophysical Properties ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Ammonium Ions ◽  
Enantiomerically Pure ◽  
Binding Process ◽  
High Affinity ◽  
Enantiomeric Recognition ◽  
Chiral Species

Enantiomerically pure dimethyl- and diisobutyl-substituted phenazino-18-crown-6 ligands bind metal and ammonium ions and also primary aralkylammonium perchlorates in acetonitrile with high affinity, causing pronounced changes in their luminescence properties. In addition, they show enantioselectivity towards chiral primary aralkylammonium perchlorates. The possibility to monitor the binding process by photoluminescence spectroscopy can gain ground for the design of very efficient enantioselective chemosensors for chiral species. The observed changes in the photophysical properties are also an important tool for understanding the interactions present in the adduct.

scholarly journals Snapshots of a Non-Canonical RdRP in Action

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1260
Author(s):  
Diego S. Ferrero ◽  
Michela Falqui ◽  
Nuria Verdaguer
Keyword(s):  
Metal Ion ◽  
Rna Viruses ◽  
Ion Binding ◽  
Genome Replication ◽  
Metal Ion Binding ◽  
Insect Virus ◽  
X Ray ◽  
Template Strand ◽  
Nucleotide Incorporation ◽  
Elongation Process

RNA viruses typically encode their own RNA-dependent RNA polymerase (RdRP) to ensure genome replication and transcription. The closed “right hand” architecture of RdRPs encircles seven conserved structural motifs (A to G) that regulate the polymerization activity. The four palm motifs, arranged in the sequential order A to D, are common to all known template dependent polynucleotide polymerases, with motifs A and C containing the catalytic aspartic acid residues. Exceptions to this design have been reported in members of the Permutotetraviridae and Birnaviridae families of positive single stranded (+ss) and double-stranded (ds) RNA viruses, respectively. In these enzymes, motif C is located upstream of motif A, displaying a permuted C–A–B–D connectivity. Here we study the details of the replication elongation process in the non-canonical RdRP of the Thosea asigna virus (TaV), an insect virus from the Permutatetraviridae family. We report the X-ray structures of three replicative complexes of the TaV polymerase obtained with an RNA template-primer in the absence and in the presence of incoming rNTPs. The structures captured different replication events and allowed to define the critical interactions involved in: (i) the positioning of the acceptor base of the template strand, (ii) the positioning of the 3’-OH group of the primer nucleotide during RNA replication and (iii) the recognition and positioning of the incoming nucleotide. Structural comparisons unveiled a closure of the active site on the RNA template-primer binding, before rNTP entry. This conformational rearrangement that also includes the repositioning of the motif A aspartate for the catalytic reaction to take place is maintained on rNTP and metal ion binding and after nucleotide incorporation, before translocation.

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